Mixing machine



May 27, 1930.

P. P. YOHE MIXING MACHINE Filed April 9, 1927 '7 Sheets-Sheet 2 P. P.YOHE MIXING MACHINE May 27, 1930.

Filed Apri1'9, 1927 7 Sheets-Sheet j77/e/1fa7" 1 1. ofie ZZ 171 2: W

- May 27, 1930.

Filed April 9, 1927 7 Sheets-Sheet 8 2 9 9 W 4 5 9 ad w /M a l M/ v a +vU 7 m f TH, m m M llii illfli' my 271 8 f0? Pew/3 z:

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MIXING /MACHINE Filed April 9, 1927 '7 Sheets-Shae? 5 P. P. YOHE MIXINGMACHINE May 27, 1930.

Filed April 9, 1927 7 SheetsShee:

May 27, 1930.

' P. P. YOHE MIXING MACHINE Filed April 9, 1927 7 Sheets-Sheet fin an/arPerr fyaie strength. 1

I In the accompanying drawings, which il- Patented May 27,: 1930 UNITEDSTATES PATENT ()FFHCE PERRY I. YOHE, 01f MINNEAEOLIS, MINNESOTA ASSIGNQRTO KOEHRING COMEANY, OF MILWAUKEE, WISCO NSIN, A CQRPORAT ION mxzneMACHINE Application filed April 9,

My present invention has for its object to provide an automatic concretemixer or the like and timing mechanism therefor.

To the above end, the invention consists of the novel devices andcombinations of devices hereinafter described and defined in the claims.

As is well known, the strength of concrete depends a great deal on theproper mixing of the materials and that all batchesor charges in a givenjob should be alike in order to semachine for mixing a batch aresuccessively and automatically repeated in timed elation. The timing ofthe mixing of a'batch of concrete may be varied, at will, but.when themixeris once set for a predetermined time, each successive batch will betimed alike until the timing is again changed, and when the concrete hasset, will have a uniform lustrate the invention, like characters 'indi-'cate like'parts throughout the several views.

Referring to the drawings: Fig. 1 is a right side elevation of a concrete mixing machine having the invention embodied therein, some partsbeing shown in different positions by means of broken lines;

Fig. 2' is a rear endelevation of the machine with some parts removedand other parts broken away;

Fig. 3 is .a detail view with some tioned on the line 33 of Fig. 2;

'Fig. 4 is a detail view with some parts sectioned on the line*44 ofFig. 1, on an enlarged scale;

Fig. 5 is a detailrview partly in side parts secshaft 19, axially aligneleva- 1927. Serial No. 182,515.

tion and partlv in section taken on the line 5-5 of Fig. 4;

Fig. 6 is a fragmentary detail view with I some parts sectioned on theline 6--6 of Fig. 5;

Fig. 7 ,is a fragmentary detail i iew with some parts sectione d on theline 77 of Fig. 1, on an enlarged scale;

Fig. 8 is a side elevation of the delivery [spout and parts associatedthe ewith, some parts being shown in diflerent positions by means ofbroken lines;

Fig. 9 is a view principally in section taken on the line 99 of Fig. 1,on an enlarged scale;

Fig. 10 is a view rincipally in elevation with some partssectioned onthe line 10-10 of Fig. 9, and with the intermediate head removed; 1

Fig. 11 is a view' principally side elevation with some partssectionedon the irregular line 11-'11 of Fig. 9;

Fig. 12 is a detail view with some parts sectioned on the line 1212 ofFig. 9;

Fig. 13 is a fragmentary view showing the timing clutch; and

Fig. 14 is a detail view in section taken on.

the line 1414 of Fig. 12.

The numeral 15 indicates a truck on which a mixing drum 16 is mounted onrollers,'not shown, to rotate about a horizontal axis which extendslongitudinally of said truck at the transverse center thereof, andhaving a pair of external axially spaced ring gears 17. -An internalcombustion engine 18 is mounted on the truck I5-at the front and rightside of the mixing drum 16. A stub of the engine 18, 1s journaled in aclutch housing 20 on said engine and a bearing in a standard 21 on the.truck 15. The stub shaft 19 is connected to the crank shaft of theengine 18, at will, by a manually-operated ed with the crank shaft"clutch,only the operating lever 22 of which 7 is shown. Keyed to thestub shaft 19 is a pinion 23 which meshes with-a gear 2 4. keyed to thefront end of a drum drive shaft 25, journaled in a'bearing on thestandard 21, and a bearing in a standard 26 on the rear end of the truck15. Pinions 27 on the shaft 25 mesh with the ring gears 17 and completethe indicated by full and broken lines in Fig. 1.

The charging skip 28 is raised and lowered by means of a pair of cables30 having one of their ends attached to said skip and their a hoistshaft. 32 journaled in bearings on a frame 15 carried by the truck 15.The hoist shaft 32 is operated by a cable 33, one end of which isattached to a hoist sheave 34 on said 'shaft and a winding drum 35 looseon the drum drive shaft 25. Co-operating with the winding drum 27 forsecuring the same to the shaft 25, at will, is a friction clutch 36having co-operating toggles 37 attached to a shipper collar 38 on saidshaft. A clutch shipper lever 39, fulcrumed on a bearing on the truck15, is provided for operating the shipper collar 38 to set and releasethe clutch 36.

For controlling the unwinding movement of the drum 27 when the clutch 36is released, said drum is provided with a braking surface 40 to which isapplied. a brake band 41 having at its ends outturned apertured ears 42,one of which is rigidly secured to a standard 43 on the truck 15. Thebrake band 41 is operated by a screw 44 that is journaled in a standard45 on the truck 15 and extends loosely through the" apertured ears 42,and has screw-threaded engagement with a nut-acting member 46 on thestandard 43. A collar 47, on the screw 44, engages the loose ear 42 formoving the same toward the fixed ear 42 under the action of the screw 44to frictionally clamp the brake band 41 onto the braking surface 40. Anoperating lever 48 is intermediately secured to the screw 44. A coiledspring 49, anchored tothe truck 15, is

attached to the long end of the lever 48 and under strain to move saidlever, and thereby rotate the screw 44 to set the brake band 41 on thebraking surface 40. On the short end of the lever 48 is a cam pin 50which works in a camsslot 51 on a bell-crank extension 52 on the handlever 39 for operating the lever 48 and thereby releasing the brake band41, as

will hereinafter appear.

A discharge spout 53 is intermediately secured to a transverse rockshaft 54 journaled in bearings 55 on standards 56 on the truck 15 ,atthe rear of the mixing drum 16 for movement to and from an inoperativeposition, as

D shown by full lines in Figs. 1 and 8. The receiving end of thedischarge spout 53, when in an operative position, extends into therearor discharge end of the mixing drum 16, as

shown by broken lines in Fig. 1. For frictionally holdin the dischargespout 53 where set, one 0 its bearings 55' is split and from thedrumdrive shaft 25 by a gear 62' on said shaft-61, with which meshes a pairof diametrically opposite opposing front and rear pinions 63 loose onthe shaft 25. Keyed to the shaft 25, between the pinions 63, is adouble-acting friction cone clutch 64 arranged'to be set in a neutralposition or in contact with either one of the internal friction surfaces65 in the pinions 63. The clutch 64 is provided with a shipper collar66.

To automatically release the winding drum 27 when the charging skip 28reaches its uppermost position, as indicated by broken lines in Fig. 1,the lever 39 is provided with a forwardly-projecting plunger 67, therear end of which is intermediately pivoted thereto andarranged forendwise sliding movement in a bearing on the standard 21, and isprovided at its outer or free end with a head 68 arranged to be engagedby :1 lug 69 on said skip. c

For operating the shipper collar 66 and hence the clutch 64 there isprovided a shipper lever 7 0 pivoted to the truck 15 and extendingbetween a pair of tripping lugs 71 and 72 on a pair of radial arms 73 inbell crank arrangement on the shaft 54. Normally, the clutch 64 is inneutral position. By moving the lever 7 O to the left in respect to Fig.8 the clutch 64 will engage the rear pinion 63 and thereby operate therock shaft 54 from the shaft 25 through the gear 62, shaft 61, and belt58. This movement of the rock shaft 54 will swing the discharge spout 53into the mixing drum 16, as shown by broken lines in Fig. 1, and therebycause the discharge of the contents of said drum. At the completion ofthe movement of the d1scharge spout 53 into the mixing drum 16, thetripping lug 71 will engage the lever 70 and move the same to the rightand thereby position the clutch 64 in neutral position and'st-op furthermovement of the rock shaft 54 and to. At the completion of'the movementof the discharge spout 53 into an inoperative posithe clutch 64 toengage the tion, the tripping lug 72 will en age the lever 1 70 and movethe same to the 1e and thereby position the clutch 64 in neutralposition and stop further movement of the rock shaft'54 and hence thedischarge spout 53.

, tion.

Said unit includes a rotatable head 74 having a peripheral tripping lug75 arranged to engage a roller-equipped abutment 76 on an upright lever77 pivoted to the back of a housing 7 8 on the truck 15 for swingingmovement in substantially the same plane as the lever 39 and,having itsupper end connected by a link 79 to said lever 39. The action of thetripping lug 75 on the abutment 76 is to operate the lever 39, by meansof the lever 77 and link 79, to set the clutch 36, release'the brakeband 41, and reset the plunger 67 for the charging skip 28. The unitalsoincludes a pair of rotatable heads 80 and 81 having diametricallyopposite peripheral tripping lugs 82 and 83, respectively, the former ofwhich, is arranged to engage a roller-equipped abutment 84 on a lever85, and the latter of which is arranged to engage a roller-equippedabutment 86 on a lever 87. The lever 85 is located forward of the head80 andthe lever 87' is locatedrearward of the head 81, and which levers85 and 87 are mounted for movement in the plane of rotation of the heads80 and 81, respectively. The lever 85 is mounted on the same pivot pinas the lever 77 and the lever 87 is pivoted to the housing 78. A link 88connects the two levers 85 and 87 for common movement.

The abutments 76, 84 and 86 are in the form of bell-cranks pivoted tothe levers 77 85 and 87, respectively, and yieldingly held .by coilsprings 89 against stop shoulders 90 on said levers to rigidly hold saidabutments when engaged by the respective tripping lugs 7 5, 82 and 83during the rotation of the heads 74, 80 and 81 in the direction of thearrows marked thereon in Figs. 10 and 11. When the heads 74, 80 and 81are rotated in reverse directions from the arrows marked thereon inFigs. 10 and 11, the abutments 7 6,84 and 86 will yield to permit thetripping lugs 75, 82 and 83 to pass the same. The levers .77, 85 and 87,as shown in Figs. 10 and 11, are in neutral position. A link 91 connectsthe levers and 87 for common movement. As shown in Fig. 1, the levers70, 85 and 87 are in neutral position as well as the clutch 64.

The following connections are provided for rotating the heads 74, 80 and81 from the tances from the clutch-settin drum drive shaft 25 at theproper speed, to

wit: a rock shaft 92, to the inner end portion of which said heads areke'yed at the back of the housing 7 8. The shaft 92 extends transverselythrough the housing 78 and is journaled in a bearing 93 formed with theinner wall of said housing, and a short tubular shaft94'journaled in ahub-like bearing 95 in the front wall of said housing. Loosely journaledon the shaft 92, within the housing 78, is a clutch member 96, andco-operating with said clutch member is a clutch member 97'keyed to theshaft 92 for rotation therewith, but with freedom for axial movementinto and out of interlocking engagement with the clutch member 96. Alarge worm gear 98 is keyed to the hub of the clutch member 96 andmeshes with a worm 99 keyed to a shaft 100 which extends parallel to thedrum drive shaft 25-and is journaled \in bearings on the standard 26 andrear wall of the housing78. The shaft 92 is driven from the shaft 25 bya sprocket 'chain 101 which runs over a relatively small sprocket wheel102 on the rear end of the shaft 25 and a relatively large sprocket who1 103 on the shaft 100.

Normally the clutch member 97 is held interlocked with the clutch member96 by a fixed clutch-setting cam pin 104 in the front .wall of thehousing 78 and a co-operating cam-acting finger 105 having a hub 106mounted on the hub of the clutch; member 97 and keyed for rotationtherewith, (see Figs. 12 and 14). During the forward rotation of therock shaft 92, the finger 105 is -moved therewith out of engagement withthe cam pin 104'in the arc of a circle, the center of which is at theaxis of said shaft. During. this movement of the finger 105, the sameengages an adjustable clutch-releasing cam pin 10'? which extendsradially vfrom a hub 108-on the inner end of the tubular shaft 94 with acam action which moves the clutch member 97 axially out of engagementwith the clutch member 96 and thereby stops further. rotation of theshaft 92. At the time the clutch member 97 is released from the clutchmember 96, it is givena backward rotafinger 105 to again engage the pin104 and move'the clutch member 97 into interlocking engagement with theclutch member 96. This spring 109 is anchored to a pin 110 secured tothe housing 78 and attached at 111 to the hub 108 which extends withinsaid spring. During the initial rotation of the rock shaft 92, thespring 109 is placed under tension. 1

To rigidly hold the tubular shaft 94 and hence the clutch-releasing campin 107 and to set said pin different, circumferential dispin 104, thetubular shaft 94, outward of t e housing 7 8, is provided with a handcrank 112 having in its hand-piece 113 a spring-projected bolt 114 95and keyed thereto.

The bores 115 represent different periods of time for one completeoperation of the machine which includes the mixing of a batch in themixing drum 116, and for the purpose of this case it may be assumed thateach bore 115 represents one minute, with zero 'at the bottom of theface plate 116. As shown, the hand crank 112 is so set that it will takethree minutes for one complete operation of the machine in which a batchof concrete has been mixed; By adjusting the hand crank 112 either tothe right or the left, the clutchreleasing cam pin 107 may be setdifi'erent distances from the clutch-setting cam pin 104.

The operation of the concrete mixer just described may be brieflydescribed as follows: After the engine 18 has been started, the operator sets the clutch connecting the engine shaft to the stub shaft 19by means of the hand lever 22 to operate the drum drive shaft" 25. Atthis time, the skip 28 is in a loading position, as shown by full linesin Fig. l, and it may be assumed that it contains the necessarymaterials for a batch of concrete to be -mixed, the clutch 36 .andclutchi member 97 are set, the clutch 64 is neutral, the discharge spout53 is in an inoperative position, as shown by full lines in Figs. 1 and8, and the tripping 'lugs '75, 82 and 83 are positioned asshown in Figs.10 and 11.

Under the initial rotation of the shaft 25, the tripping lug 83 engagesthe abutment 86, moves the lever 87 rearward, and through theconnections 91 and 70, moves the clutch 64 into engagement with the rearpinion 63, and thereby operates the connections to the rock shaft 54,which moves the discharge spout 53 into the mixing drum 16. The drum 16is, of course, empty at the time the machine is started and hence therewill be no discharge therefrom the first time the discharge spoutv 53 ismoved into an operative position. During the final movement of thedischarge spout 53 into the mixing drum 16, the tripping-lug 71 operatesthe lever '70 which returns the clutch 64 to neutral osition and stopsfurther movement of said spout with the same set in an operativeposition. -After the tripping lug 83 is moved out of engagement with theabutment 86' and under futher rotation of the shaft 92, the tripping lug7 5 engages the abutment 76, operates the lever 77 which sets the clutch36, and positions the plunger 67 to be engaged by the lug 69 on thecharging skip At substantially the same time that the tripping lug 75engages the abutment 7 6, the tripping lug 82 engages the abutment 84,op-

' crates the lever 85 which through the connections 88, 87 and 91operates the lever 70 which moves the clutch 64into engagement with thefront pinion 63, and thereby operates the rock shaft 54 which moves thedischarge spout 53 out of the mixing drum 16. During the final movementof-the discharge spout 53 to an inoperative position, the lug 72operates the lever 70 and returns the clutch 64 to neutral position andthereby stops further movement of'said discharge spout.

At the time the clutch 36 is set by the action of the tripping lug 75 onthe abutment 76, the brake band 4L is released and the winding drum 35starts to rotate. Under the rotation of the drum 35, which has beenstarted by the setting of the clutch 36, the cable 33 is wound thereon,which lifts the skip 28 into a posi. tion, as indicated by means ofbroken lines in Fig. 1, and causes its load to be discharged into therotating mixing drum 16. During the final lifting movement of thecharging skip 28, its lug 69 engages the plunger head 68 and moves theplunger 67 rearward, and

thereby operates the lever 39 to release the clutch 46 and stop furtherlifting movement of said skip, and allows the same to return to itsloading positionunder the action of gravity. At the time the clutch 36is released by the lever 39 under the action of the plunger 67 producedbythe charging skip 28, said lever sets the brake band 41 onto thebraking surface 40 and thereby controls the unwinding of the cable 33from the drum 35 to prevent the charging skip 28 from moving too fastduring its return movement. The movement of the lever 39 by the plunger67 also operates the lever 77 by the link connection 79 and therebypositions its abutment 76 to be engaged by thetripping lug 7 5, asindicated in Fig. 10, during the next operation of the machine. Duringthe forward rotation of the rock shaft 92, the spring 109 is placedunder tension and the cam finger 105 is moved from theclutch-setting'pin 104 to the clutch-releasing pin 107. The trippinglugs 75, 82 and 83 havealso acted in their proper order on the trippingabutments 7 6, 84 and 86, respective- 131. At the completion of theallotted period of time for/the mixing of the concrete in the drum 16,the cam finger 105 engages the clutch-releasing pin 107 and is movedthereby away from the worm gear 98 which releases the clutch member 97from the driven clutch member '96. When the clutch member 97 is releasedfrom the clutch member 96, the s ring 109 becomes active and returns thecam nger 105 to the cam-setting pin 104 which again, acting on saidfinger, moves the clutch member 97 into interlocking engagement with theclutch member 96. This action of the spring 109 also turns the shaft 92back wards and resets the tripping lugs 75, 82 and 83. .With theresetting of the, clutch memberv 97, the initial forward movement of theshaft 92 brings the tripping lug 83 into engagement with the abutment:86, operates the lever 87,

which, in turn, by the link 91 operates the charge of the mixed batch ofconcrete from the drum 16. Successive operations of the machine areidentical with the one just described.

After the hand crank 112 has been set for a predetermined time for theoperation of the machine, the same in actual usage, will be locked orcovered with a casing to prevent any one from changing the time of themachine without authority. I

The housing 78 together with the mechanisms contained therein, and theheads 74, 80

and 81, constitute in effect a timing mechanism or batchmeter, so knownin the art, inasmuch as they determine the mixing period of a batch ofconcrete in the mixing drum. I

What I claim is:

1. The combination with a mixing drum a main drive shaft therefor, aloading skip, a hoisting drum for the skip, and clutch mechanism foroperatively connecting the hoist drum with the main drive shaft for themixing drum, of timing mechanism for automatically controlling theoperation of the skip, said mechanism being directly connected withthe'main' drive shaft 'of the drum and including cam means forautomatically operating the clutch to initiate upward movement of theskip, and means adapted for operation by the skip upon its reachingitsuppermost position, to move the clutch into neutral position, wherebyhoisting action is discontinued.

2. Concrete mixing apparatus of the class described, comprising, incombination, a mixing drum, a loading skip, a discharge chute, amaindrive shaft-for operating the hereinbefore described parts, a timingshaft driven by the main drive shaft, cam heads on said timing shaft,and means for causing movement of the discharge chute and loading skipadapted to be engaged by the cams on the heads and automatically broughtinto. operation by said engagement. v

3. Mixing apparatus of the class described, comprising, in combination,a mixing drum, loading and discharging means for the drum, a main driveshaft for rotating said drum, a timing shaft-driven by the drumdriveshaft and instrumentalities operated by said timing shaft forautomatically causing operation of the discharge and loading means intimed relation to. determine the mixing period of aggregates in thedrum.

4.111 concrete mixing apparatus of'the class described, thecombination,'wit-hamixing drum, discharge chute, loading sk1p,and maindrive shaft for these parts, of a timing mechanism includinga timingshaft operatively-connected with the main dijve shaft, a

cammed head on the timing shaft for moving the discharge chute intodischarging position, another cammed head on the timing shaft for movingthe discharge chute into non-discharging position, and disposed withrelation to the first mentioned cam so that this movement takes placesubsequent to movement into discharging position and after the elapse ofa predetermined period of time, and a third cammed head also mounted onthe timing shaft for automatically initiating upwar movement of theloading skip.

5. Timing mechanism for concrete mixing apparatus comprismg, incombination, a

main timing shaft, clutch mechanism for operatively connecting saidtiming shaft with a" drive shaft of a mixer, discharging chute and.loading skip, controlling means mounted on said timing shaftand'operated-thereby, and means for automatically causing disengagementof said clutch means after the elapse of a predetermined period of time.

6. Timing mechanism for concrete mixing apparatus com rising, incombination, a timing shaft, clutc mechanism for drivably conmeetingsaid timing shaft with a rime mover in the mixing apparatus, means orautomatically causing movement of said clutch into operative, position,and means for automatically disengaging said clutch and means forvarying the relative positions of said disengaging means with \respectto the engaging means. J

7. Timing mechanism for a concrete mixer comprising, in combination,cammed heads for controlling the operation of the loading and dischargeinstrumentalities of the mixer, means for rotating said cammed heads,clutch means for setting up a driving connection be tween said headturning means and the mix- .ing apparatus, said clutch means including amovable part, means for said movable part into and out ofoperativeengagement with the remainder of the clutch mechanism, and a springafiixed to said movable clutch member and adapted to cause its return tooriginal position after said clutch member has been disengaged from theremainder of the said clutch mechanism. v

8. An attachment for concrete mixing machines having a driving member,'charging .and discharging devices andch'arging and discharging controllevers to cause actuation of the charging anddischarging devices fromthe drivin member, comprising a shaft, connections or operating theshaft from the driving member including a clutch, connections fromtheshaft for operating the 'levers in timed relation, and means forautomatically releasing the clutch and resetting the same, saidmeansbeing adjustable for different periods oftime from the resetting ofthe-clutch to the releasing of the same.

9. An attachment for mixing machines of the kind described having adriving member,

a charging control lever and a discharging control lever, comprising adrive shaft, connections for operating the shaft from the driving memberincluding a clutch, connections from the shaft for operating the leversin timed relation, automatic means for setting the clutch, automaticmeans for releasing the clutch, and a spring arranged to be placed undertension by the clutch durin the rotation of the shaft to return theclutc 1 when released to its initial position and cause reclutching ofthe same by the automatic clutch resetting means.

7 10. An attachment for concrete mixing machines having a drivingmember, a charging control lever and a discharging control lever,comprising a shaft and connections for operating the shaft from thedriving member including a clutch, connections from the shaft foroperating said levers in timed relation, automatic means for setting theclutch, automatic means for releasing the clutch, and a spring arrangedto be placed under tension during the rotation of the shaft to .returnthe released clutch to its resetting position, said automatic means forreleasing the clutch being adapted tobe adjusted with respect to theautomatic clutch setting means for resetting the clutch to vary theperiod of time between clutch setting and releasing operations.

11., An attachment for con crete mixing machines having a mixing drum, acharging device and a discharging device, a driving member for operatingthe drum charging and discharging devices, and control levers forcausing actuation of the charging and discharging devices, saidattachmen comprising ashaft, connections for operating the shaft fromthe driving member including a shiftable clutch, connections from theshaft for operating the levers of the mixing machine in timedfrelation,a clutch setting member, a clutch releasing member, and a springarranged to be placed under tension by "the clutch during theactuationof the levers to return the clutch from its released position toitsresetting position when released by the clutch releasing member.

12. An attachment for mixing machines of the character describedprovided with a driving member, amixing drum, charging and dischargingdevices therefor, a charging control lever and a discharging controllever, said attachment comprising a shaft, connections for operating theshaft from the driving member including a clutch, connections from theshaft for operating the levers in timed relation, a clutch settingmember, a clutch releasing member and a spring arranged to be placedunder tension to return the clutch when released from its releasingposition to itsresetting position and cause resetting by the clutchsetting member. said clutch releasing member being adapted to be shiftedwith respect to the clutch setting member to vary the distance betweenthe clutch setting and clutch releasing members to vary the periodbetween clutch setting and clutch releasing operations.

13. An atta n'ment for concrete mixing machines of the kind describedhaving a driving member, a charging control lever and a dischargingcontrol level, said attachment operating the respective levers in timedrelation, means for automatically releasing the clutch, automatic meansfor reversing the shaft to return the clutch to resetting posi: tion,and automatic means for resetting the clutch.

14. An attachment for concrete mixingmachines' of the kind describedhaving a comprising a shaft, a connection for operating the shaft fromthe driving member of the mixer including a clutch, levers attachable tothe control levers of the mixer and having abutments, devices on theshaft of the attach- 1 driving member, a charging control lever and adischarging control lever, said attachment inent arranged to engage saidabutments for operating the respective levers in timed relation, meansfor automatically1 releasing the clutch,-means for reversingt e shaft toreturn the clutch to resetting position and reset the clutch, said meansfor releasing the clutch being adjustable with respect to the means forresetting the clutch to vary the period between charging and discharginglever actuations by the attachment.

15. In attachmentfor concrete mix ng machines of the kind describedhaving a driving member, a charging control lever and a dischargingcontrol lever, said attachment comprising a shaft, connections foroperating the shaft from the driving member of the mixer including aclutch, levers attachable to the control levers of the mixer and havingyieldable abutments, devices on the shaft of the attachment arranged toengage said abutments for operating the respective levers in timedrelation, means for automatically releasing the clutch and for reversingthe shaft to return the clutch to resetting position for resetting theclutch, said means for automatically releasing the clutch beingadjustable with respect to the means for resetting the clutch to varythe period between charging and discharging lever actuations, saidyieldable abutments being arranged to permit the devices on the shaft tomove past the whereby to discharge said drum of the mixed concrete,means for charging the drum with aggregates to be mixed therein, and acombined unit for automatically controlling the mixing period, thedischarging means and charging means, said unit compelling continuoussynchronized operation of the dis charging and charging means andcontrol- .ling the mixing cycle of the drum, said means being entirelyoperative by the driving means. 1

17. A concrete mixing machine cycle tim ing unit comprising a casing, ashaft therein, cams on the shaft, levers adapted to be actuated by thecams for controlling the charging and discharging actions of themachine, clutch means on the shaft, and knock out means for the clutchmeans to control the mixing period, said means being operative by theshaft.

18. In an automatic concrete mixing .machine cycle controlling unit, ashaft adapted to be rotated in one direction from the engine of astandard concrete mixing machine, supports for said shaft, means forrotating the shaft in the opposite direction, means for alternatelyeffecting oscillation of the shaft in opposite directions, means to varythe degree of oscillation of said shaft to control the mixing period,and actuating memberson the shaft adapted toactuate the charging anddischarging devices of the standard mixing machine during'the rotationof the shaft in one direction and non-engageable with the charging anddischarging devices during rotation'in'the other direction.

19. In combination with a concrete mixing machine, a mixing drum,charging and discharging instrumentalities therefor, an engine foroperating'said charging and discharging in'strumentalities and themixing drum, of an automatic-control unit driven by the engine forcompelling synchronized operation of the charging and discharginginstrumentalities, said unit comprising a casing, a cam shaft therein,means for rotating the shaft in one direction from the engine, springmeans for rotating the shaft in the opposite direction when releasedfrom the engine, adjustable declutching means for varying the degree ofoscillation of said shaft, and cams carried by the shaft for operatingthe discharging and charging instrumentalities when the shaft isactuated by the engine.

20. In combination with a concrete mixing device and reclutchingactionwith the main shaft.

In testimony whereof I afiix my signature.

PERRY P. YOHE,

machine, a mixing drum, a charging skip for introducing aggregates intothe drum, adischarging device for emptying the drum of the mixedaggregates, and apower shaft for actuating the drum, of a unitarycontrol device for automatically effecting operation in synchronizedrelation by the power shaft of the charging and discharging devices andpermitting a predetermined lapse of time between the charginganddischarging of the

